'use strict';

var dnsjs = require('dns-suite');
var crypto = require('crypto');
var dgram = require('dgram');

var RCODES = {
  0: 'NOERROR'
, 3: 'NXDOMAIN'
, 5: 'REFUSED'
};

function logQuestion(packet) {
  var flags = "";

  // TODO opcode 0 QUERY rcode 0 NOERROR
  console.info(';; ->>HEADER<<- [opcode: ' + packet.header.opcode + ', status: ' + (RCODES[packet.header.rcode] || packet.header.rcode) + '], id: ' + packet.header.id);
  if (packet.header.tc) { console.info("Truncated [tc] (we don't know the normal way to print a tc packet... you should record this with -o tc-packet.dig and send it to us)"); }
  flags += ";; flags:";
  if (packet.header.qr) { flags += " qr"; }
  if (packet.header.aa) { flags += " aa"; }
  if (packet.header.rd) { flags += " rd"; }
  if (packet.header.ra) { flags += " ra"; }
  flags += "; QUERY: " + packet.question.length + ", ANSWER: " + packet.answer.length + ", AUTHORITY: " + packet.authority.length + ", ADDITIONAL: " + packet.additional.length;
  console.info(flags);
  if (packet.header.res1) { console.info("[res1] (we don't know how to print a packet with res1 yet)"); }
  if (packet.header.res2) { console.info("[res2] (we don't know how to print a packet with res2 yet)"); }
  if (packet.header.res3) { console.info("[res3] (we don't know how to print a packet with res2 yet)"); }
  // {"id":32736,"qr":1,"opcode":0,"aa":0,"tc":0,"rd":1,"ra":0,"res1":0,"res2":0,"res3":0,"rcode":5}
  //console.log(JSON.stringify(packet.header));
  console.info('');
  console.info(';; QUESTION SECTION:');
  packet.question.forEach(function (q) {
    console.info(';' + q.name + '.', ' ', q.className, q.typeName || ('type' + q.type));
  });
}

function resolve(queryAb, opts) {
  var handlers = {};
  var nameservers;
  var nameserver = opts.nameserver;
  var index;
  var udpType;
  var receivedMessage;
  if (!nameserver) {
    nameservers = require('dns').getServers();
    index = crypto.randomBytes(2).readUInt16BE(0) % nameservers.length;
    nameserver = nameservers[index];
  }
  udpType = /:/.test(nameserver) ? 'udp6' : 'udp4';
  var server = dgram.createSocket({
    type: udpType
  , reuseAddr: true
  });
  server.nameserver = nameserver;

  handlers.onError = function (err) {
    if (opts.onError) { opts.onError(err); } else { throw err; }
    server.close();
  };
  handlers.onMessage = function (bin) {
    receivedMessage = true;
    if (!opts.mdns) {
      clearTimeout(server._timeoutToken);
      server.close();
    }

    if (opts.onMessage) { opts.onMessage(bin); }
  };
  handlers.onListening = function () {
    /*jshint validthis:true*/
    var server = this;

    if (opts.mdns || '224.0.0.251' === server.nameserver) {
      server.setBroadcast(true);
      server.addMembership(server.nameserver || '224.0.0.251');
    }

    if (opts.onListening) { opts.onListening.apply(server); }

    server.send(Buffer.from(queryAb), opts.port, server.nameserver, function () {
      if (opts.onSent) { opts.onSent({ port: opts.port, nameserver: server.nameserver }); }
    });
  };
  handlers.onClose = function () {
    if (opts.onClose) { opts.onClose(); }
  };

  server.on('error', handlers.onError);
  server.on('message', handlers.onMessage);
  server.on('listening', handlers.onListening);
  server.on('close', handlers.onClose);

  // 0 dns request
  // 53 dns server
  // 5353 mdns
  if (opts.mdns) {
    server.bind(opts.port /*5353*/);
  }
  else {
    server.bind(0);
  }
  var ms = opts.timeout || (5 * 1000);
  server._timeoutToken = setTimeout(function () {
    if (!receivedMessage && opts.onTimeout) { opts.onTimeout({ timeout: ms }); }
    server.close();
  }, ms);
}

function resolveJson(query, opts) {
  var queryAb;
  try {
    queryAb = dnsjs.DNSPacket.write(query);
  } catch(e) {
    if ('function' === typeof opts.onError) { opts.onError(e); return; }
    throw e;
  }

  //console.log('[DEV] nameserver', opts.nameserver);
  var options = {
    onError: opts.onError
  , onMessage: function (nb) {
      var packet;
      try {
        packet = dnsjs.DNSPacket.parse(nb.buffer.slice(nb.byteOffset, nb.byteOffset + nb.byteLength));
      } catch(e) {
        if (opts.onError) { opts.onError(e); return; }

        console.error("[Error] couldn't parse incoming message");
        console.error(e);
        return;
      }

      opts.onMessage(packet);
    }
  , onListening: opts.onListening
  , onSent: opts.onSent
  , onClose: opts.onClose
  , onTimeout: opts.onTimeout
  , mdns: opts.mdns
  , nameserver: opts.nameserver
  , port: opts.port
  , timeout: opts.timeout
  };

  return resolve(queryAb, options);
}

module.exports.resolve = resolve;
module.exports.resolveJson = resolveJson;
module.exports.request = resolve;
module.exports.requestJson = resolveJson;

module.exports.logQuestion = logQuestion;